Process of producing sulphur



Patented ar. 22, 1932 UNITED STATES PATENT OFFICE NILS ERIK LENANDER AND INGVALD RYEN, F LOKKEN VERK, NORWAY, ASSIGNORS TO PATENTAKTIEBOLAGET GRONDAL-RAMEN, OF STOCKHOLM', SWEDEN PROCESS OF PRODUCING SULPHUR No Drawing. Application filed August 27, 1928, Serial No. 303,370, and in Sweden August 31, 1927.

In the smelting for'instance of copper pyrites by so called pyritic melting the largest part of the sulphur driven out 1n the furnace is removed in the form of sulphurous acld, which generally is not utilized, but, if let out in the open air, causes serious inconveniences; the smelting of pyrites for that reason only can take place at isolated locations.

The present invention relates to a process, by means of whichthe smelting of pyrites can be carried out practically anywhere without causing the said inconvenience, while at the same time affording very great advantages which make it remunerative, even if the pyrites does not contain any copper.

According to the invention the pyrites 1s smelted in a closed shaft furnace together i with a sufficiently large quantity of solid reducing means for instance coke, that the sul phur, driven out in the process, escapes in the form of elemental sulphur.

The smelting process proceeds substantially as follows: Presuming that the furnace shaft is charged with pyrites, fluxes if required and coke in alternate layers and that blast is introduced through the twyers, the sulphur and iron, which are present in the charge at the level of the twyers and in. the furnace zone thereabove, are oxidized to S0,, and Fe O The resulting temperature is so high, that the charge will melt, forming matte and slag, which are removed from the furnace in the usual manner.

The hot gases produced in the melting or oxidation zone and principally consisting of nitrogen and sulphurous acid with or without a little quantity of oxygen, in their continued noted is s S0 and incidentally of COS. It is conducted from the furnace to a condensing apparatus, where S is condensed. The gas thus treated can be passed to waste through a chimney and causes, if the chimney is of a sufficient height, no inconveniences to the surrounclings. It may, however, also be utilized,

way.

' The carrying out of the process as described may of course be modified according to the composition of the ore and other circumstances. If for instance the ore does not contain a suflicient quantity of sulphur to supply the fuel necessary for the accomplishment of the melting, the amount of the solid reducing used means, must be increased, so that part of it reaches the level of the twyers for the purpose of generating at that place the required increase of heat, likewise, an increased amount of the solid reducing means is necessary if supplemental S0 is introduced through the twyers. It has, however, been ascertained that the use of a too great surplus of reducing means, for inst. of coke, is not advantageous, because combinations of COS then frequently are formed.

By means of the process described other ores than copper pyrites can be treated, for inst. pyrites which does not contain any copper.

The sulphur in pyrites as well known, is much cheaper than common sulphur; for that reason it has long been desirable especially concerning pyrites ores which are situated so that their transportation will be expensive, to produce sulphur from pyrites but up to date an economical method heretofore'has not been developed. By-the process above describec,

an economical production of sulphur from pyrites, however, ispossible. If the percentage of iron in the ore to be treated is relatively small a slag, poor in iron, is obtained, while the percentage of iron in the matte becomes high. After a roasting of the said matte, whereby the gases from the roasting process are supplied to the melting furnace with the blast, the roasted matte may be submitted to a chloridizing roasting and lixiviation, whereupon a residue of burnt pyrites a purple ore with a very high percentage of iron is obtained. In this manner it is possible to recover not only the sulphur of the ore but also a large percentage of its contents of iron as a valuable iron-combination having a high percentage of iron. Such a treatment is quite in accord with that described above.

Another-ore, which also can be treated in the same manner and in the treatment of which remarkable advantages may result, is pyrites containing copper and arsenic.

Hitherto it has been relatively expensive to work up such an ore on account of its contents of arsenic, because it has been necessary to remove the arsenic before the ore could be utilized by smelting.

By the process described above the ore can be melted without further trouble, whereby the greatest part of tie arsenic'and one atom of the sulphur of th pyrites are removed at a temperature of 7O0 800 C. The remaining sulphur in the form of FeS is consumed in the manner described above for the melting operation, and the resulting sulphurous acid as well as arsenious acid are reduced by the reducing means, whereby furnace gases, essentially consisting of N, CO2, S and As in the reduced form will be removed. The sulphur and the arsenic are condensed, forming a sulphur-arsenic-combination, which can be stored in a closed chamber without'dangerous possibilities or, if desired, the combination may be converted into its constituent elements, viz., sulphur and arsenic.

The resulting. matte, which besides the copper contains a little quantity of arsenic, is roasted; the gases thereby developed, con taining combinations of sulphur and arsenic, are introduced in the smelting furnace with the blast, relduced by the reducing means, and utilized.

If the gas escaping from the smelting furnace should contain any H S the ore and also the reducing means for inst. coke in the furnace ought to be dried. or heatedfor the purr i n ihe-hyd :c bonsrem ined ---'.inthem.'

But even if the charge is free from water and hydrocarbons, the escaping gas will contain a quantity of H 8, although it may be a small one, depending -;.upon thezamount of .Qmoisture intheblast.-f1" This3 cause-safer theformation. of- .sulphuretted. hydrogen could,

however, be removed by drying of the blast,

but the cost therefore would become heavy.

In place of the drying'of the charge and the air another means may be used for the purification of the escaping gas from all sulphur combinations, whereby these combinations also could be utilized. If a copper pyrites is smelted, a matte is produced, and if that matte is roasted partially, chloridized and lixiviated a solution of CuCl will be. obtained.

If this solution is treated for instance in a precipitating tower through which the so-- lution is conducted in a direction opposite to that of the escaping gas, the latter will become free from its combinations of sulphur because sulphuretted copper or c'hlorur of copper is formed.v

In the treatment of copper pyrites, also containing a relatively large percentage of zinc, the slag sometimes contains copper and zinc. Such a slag can be subjected to a chloridizing roasting together with the partially roasted matte and a subsequent lixi-. viation, whereby the copper as well as the zinc may be recovered.

In place oftreating the partially roasted matte by a chloridizing roasting and a subescaping gases a part of the roasted matte may be chloridized and lixiviated.

The'gases obtained .in the treatment according to the Bessemer process may also be introduced into the smelting furnace for the purpose of making them harmless or for their utilization.

In the preceding part of this specification three kinds of ore are stated, which may be treated according to the present invention; it is, however, possible also to treat other pyrites in the same manner i. e. those containing volatilizable or reducible metals.

The furnace suitable for the process now described as already stated must beprovided with a closed throat. Care must also be taken that that zone of the furnace, where the reduction and distillation of the volatile components of the ore takes place, is so s acious that the said processes become quite e ective.

The outlet openings for the gases ought to be arranged in such a manner, that the speed of the gases does not become so great, that powder from the charge is swept away witlrthein. In some cases itmaybe suitable, to conduct the gas from the furnace throu h aCott-rell-apparatus for .separationof t e dust, which still rests in thegas, for. inst.

i rthe treating of ;z'inciferens pyrites. ta Having now particularly "described :the

nature-of :our inventiomand the-*mannerof its operation, what we claim is:

1. A process of producing sulphur from pyritic ores in a shaft furnace with a closed throat, which comprises mixing the ore and a solid reducing means, blasting air upward through the mixture, melting the pyritic ore, said solid reducing means being added in sufficient quantity to reduce the sulphur dioxide formed to elemental sulphur and to combine with any excess oxygen in said blasting air, drawing off the non-volatile constituents of said ore in molten condition, and condensing the volatile constituents to separate them from the volatile non-condensibleconstituents.

2. A process of producing sulphur from pyritic ores in a shaft furnace with a closed throat, which comprises mixing the ore and a solid carbonaceous reducing means, blasting air upward through the mixture, regulating the quantity of solid carbonaceous reducing means and blasting air according to the composition of said ore, melting the pyritic ore, drawing off the non-volatile constituents of said ore in molten condition, and condensing the volatile constituents to separate them from the volatile non-condensible constituents.

3. A process of producing sulphur from pyritic ores in a shaft furnace with a closed throat, which comprises mixing the ore and a solid carbonaceous reducing means, blasting air through the mixture, melting the pyritic ore, forming a matte of constituents of said ore, drawing 05 the non-volatile constituents of said ore in molten condition, forming matte of the same, roasting said matte, blasting gases from said roasting with said air through said mixture, and condensing the volatile constituents of said pyritic ores to separate them from the volatile non-condensible constituents.

4. A process of producing sulphur from sulphide ores which comprises, passing oxygen-containing gas through a charge of sulphide ore and coke to oxidize the fixed sulphur of that portion of the ore not used for matte formation, providing said coke in suitable amount to substantially reduce the oxidized sulphur to elemental sulphur, forming a matte of non-volatile constituents of said ore, melting the ore, drawing off the nonvolatile materials in a molten condition, and condensing the condensible volatile materials.

5. A process of producing sulphur from sulphide ores which comprises, blasting air through a charge of sulphide ore and coke to oxidize the fixed sulphur of that portion of the charge not used for matte formation, melting said ore by the heat developed by the oxidizing action of the oxygen of the air, providing said coke in suitable amount to substantially reduce the oxidized sulphur to elemental sulphur and to supply such supplemental fuel as is necessary to melt said ore, forming a matte of non-volatile constituents of said ore, drawing off the non-volatile materials in a molten condition, and condensing the volatile materials to separate them from the volatile non-condensible materials.

6. A process of producing sulphur from. sulphide ores which comprises, passing oxygen-containing gas through a charge of sulphide ore and solid carbonaceous reducing agent to oxidize the fixed'sulphur of that portion of the charge not used for matte formation, said solid carbonaceous reducing agentbeing provided in suitable amount to substantially reduce the oxidized sulphur to elemental sulphur and being substantially free of hydrocarbons, forming a matte of nonvolatile constituents of said ore, melting said ore, drawing off the non-volatile materials in a molten condition, and condensing the condensible volatile materials.

NILS ERIK LENANDER.

INGVALD RYEN.

EERTI FECATE (9F CORRECTION.

Patent Ne. 35 Granted March 22, 1932, to

MLS ERIK LENANDE-R ET AL.

it is hereby certified? sthat errer appears in the printed specification of the above numbered patent requiring correction as fellows: Page In, iine 78, for "used means reae: means used; page 3, lines 35 and 36, claim 3 strike out the words and comma forming meme 0% the same"; and that the said Letters Patent shculd be read with these corrections therein that the same may eenform to the record ei rhe case in Recent @ffice.

Signed and seeied this Uih deg! cf May, A. D. 1932.

M. 3. Mcore,

(Seal) Acting Qemmissioner of Patents. 

